Top 4 Corn Harvest Observations

Summary:
  • Planning your 2015 corn crop begins before you even start combining your first cornfield.
  • Harvest is an opportunity to evaluate otherwise unseen disease, weed and insect pressure in your fields observed from the combine. How can those observations influence 2015?
  • How you can estimate yields before harvest even begins, and see how that estimate compares to your yield monitor. 

Top 4 Corn Harvest Observations

For many people, August represents the dog days of summer. However, when you’re a corn grower, August means something entirely different. It comes with an eagerness and anticipation of harvest. The sight of grain dust and bees wings from the cobs, the smell of fall and the sound of corn pouring out of the auger are just around the corner.

Yield Estimates

Before combining even begins, virtually every grower has established his or her own formula for predicting yields. You might not have the final number until you empty the last weigh wagon and evaluate yield monitor results, but it’s common to see who comes the closest.

The Yield Component Method, described by Purdue University, might be the most popular method to predict yield. This approach takes into account estimates of ears per acre, kernel rows per ear and weight per kernel. You can use this approach as early as R3, or the milk stage, of kernel development. And the closer you get to harvest, the more accurate your estimate.

Disease Observations

You can make several other observations once you’re in the combine cab and going through fields. It’s an opportunity to view parts of the field that may have been difficult to scout when the crop canopied. Even in dry plants, you might see symptoms of disease that developed late in the season. In 2012, Midwest Producer reported that growers noticed clouds of black and sooty dust during harvest. This turned out to be the result of different fungi that might have been present, such as anthracnose or Alternaria leaf spot.

If you notice such dust during harvest, you can submit a sample to your Extension office for identification. If they diagnose it as a fungal disease, talk with your retailer about including a fungicide, such as Stratego® YLD, in your 2015 crop input plan.

Insect Infestations

Corn rootworm (CRW) often is one of the first thoughts to come to mind when discussing insects at harvest. CRW weakens roots and stalk quality, meaning corn is more likely to break or lean over. This is evident during harvest because you have to drive at a snail’s pace, often reversing and relocating rows. This might sacrifice some of your yield because ears are more likely to drop from leaning and fallen corn stalks.

CRW resistance to the Cry3Bb1 protein, found in some Bt hybrids, is increasing. Don't assume the presence of CRW in a field of Bt corn means resistance, though. If you suspect resistance, it’s important to contact the seed company and/or trait provider. The US EPA requires seed companies and/or trait providers to investigate suspected resistance. Also, talk with your local agronomist or Extension entomologist to determine the best way to proceed. They can help you determine if you should consider an insecticide, such as Baythroid® XL, for the control of cutworm and other pests as part of your 2015 corn plan.

Weed Control

Perhaps the most noticeable observation you can make from the cab is that of weed control. Your weed control program should have held weeds back until canopy, when your corn crop took care of the rest. If there happen to be any weed escapes, they will be obvious as you roll through the fields during harvest. A herbicide program with long residual will reduce — or even eliminate — such weed escapes next year. A product such as Corvus® herbicide provides reactivation in addition to season-long residual.

The First Step

Of course, before you can make any of the above decisions, the first step is seed selection. Besides maturity rating and planting zones, you must decide between conventional or traited hybrids, and how many trait stacks you want. For example, choosing a LibertyLink® hybrid with a Bt trait means you can get outstanding weed control when treated with Liberty® herbicide, and also CRW control. It’s important to talk with your seed dealer and retailer to determine the plan that’s right for your operation. Are you also planning to harvest soybeans this year? We have information on what to look for during that harvest, too.  


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The University of Nebraska-Lincoln goes into further detail about weed management observations during harvest.


The University of Illinois summarized its 2013 mid-harvest observations. How do you think 2014 will compare?
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